This invention relates to energy-absorbing tear webbing, and more particularly to such webbing which has woven pile or tear yarn which is designed primarily for parachute harnesses and the like, but it is understood that the invention can be used for any purposes for which it is found applicable.
The use of strap webbing for absorbing shock has been proposed in the parachute art and wherever straps are employed in an environment to absorb shock, such as a window-washer harnesses.
One example of a parachute harness is illustrated in U.S. Pat. No. 2,352,036 where the several straps are temporarily attached together by thread stitching. When a force is applied between the straps, the stitching therebetween is gradually parted to absorb the shock. The intervals between the rows of stitches can be irregular to vary the shock-absorbing characteristics.
Experience has revealed that the backing straps may be physically damaged by the needle during the stitching process, and for this and other reasons it has been proposed to replace the breakable stitching with a pile yarn which is woven in and between the backing straps during the weaving process of fabricating the straps. Such a technique is illustrated by the U.S. Pat. Nos. 3,463,202 and 3,612,110. In these two patents, the pile or binder yarn passes over a group of several weft picks in one strap before transferring to the other strap, etc., except where provision is made for a buckle where the pile yarn extends unwoven along the straps for a predetermined distance.
Test have shown that such prior art webbing straps perform satisfactorily at low speeds, i.e., under 200 f.p.s. However, tearing out through the backing strap is minimized by making the straps much stronger than would otherwise be necessary. Failure of the straps to peel apart at high speeds has prevented the use of such straps in those applications where velocity of separation exceed 300 f.p.s.